CN105786276B

CN105786276B - Circular outline single layer pattern

Info

Publication number: CN105786276B
Application number: CN201610018032.3A
Authority: CN
Inventors: S.C.韩; D.索尔文
Original assignee: Synaptic
Current assignee: Synaptic
Priority date: 2015-01-12
Filing date: 2016-01-12
Publication date: 2020-08-11
Anticipated expiration: 2036-01-12
Also published as: US9910531B2; CN105786276A; US20160202826A1

Abstract

Circular, single layer sensor electrode patterns for input devices such as wearable devices are described. The sensor electrode pattern features transmitter electrodes and receiver electrodes laid out in an alternating manner such that each "receiver" electrode is surrounded by a "transmitter" electrode. The individual sensor electrodes of the described pattern are designed to provide substantially the same electrode area size across the sensor. In addition, the sensor electrode patterns are arranged to be symmetrical both with respect to the horizontal axis and the vertical axis. The provided characteristics of the sensor electrode pattern result in the sensor structure having the same absolute capacitive sensing measurement for all sensor electrodes and the same transcapacitive sensing measurement for all "pixels".

Description

Circular outline single layer pattern

Technical Field

Embodiments relate generally to input sensing, and in particular to sensing devices having circular electrode designs for capacitive sensing.

Background

Input devices, including proximity sensor devices (also commonly referred to as touch pads or touch sensor devices), are widely used in various electronic systems. Proximity sensor devices typically include a sensing area, often bounded by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. The proximity sensor device may be used to provide an interface for an electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated into or peripheral to a laptop or desktop computer). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones).

Disclosure of Invention

Embodiments of the present disclosure provide capacitive sensors. The capacitive sensor includes a sensor substrate and a plurality of sensor electrodes arranged on a first face of the sensor substrate and arranged in a symmetrical circular pattern. The plurality of sensor electrodes includes an inner circle of sensor electrodes and an outer circle of sensor electrodes arranged radially outward from the inner circle of sensor electrodes. The plurality of sensor electrodes is configured to sense an input object in a sensing area of the capacitive sensor. Each of the plurality of sensor electrodes has a substantially equal surface area.

Another embodiment of the present disclosure provides a capacitive sensor device. The capacitive sensor device comprises a sensor substrate and a plurality of sensor electrodes arranged on a first face of the sensor substrate and arranged in a symmetrical circular pattern. The plurality of sensor electrodes is configured to sense an input object in a sensing area of the capacitive sensor device. Each of the plurality of sensor electrodes has a substantially equal surface area. The capacitive sensor device also includes a processing system communicatively coupled to the plurality of sensor electrodes. The processing system is configured to perform mutual capacitive sensing by driving sensing signals on a first subset of sensor electrodes of the plurality of sensor electrodes and receiving resulting signals on a second subset of sensor electrodes of the plurality of sensor electrodes. The processing system is also configured to perform absolute capacitive sensing through the plurality of sensor electrodes. Each of the sensor electrodes from the first subset of sensor electrodes shares a boundary with a sensor electrode of the second subset of sensor electrodes.

Embodiments of the present disclosure also provide a processing system for a touch screen device. The processing system includes a sensor module communicatively coupled to a plurality of sensor electrodes. A plurality of sensor electrodes are arranged on the first face of the sensor substrate and are arranged in a symmetrical circular pattern. The plurality of sensor electrodes are configured to sense an input object in a sensing area of the touch screen device. Each of the plurality of sensor electrodes has a substantially equal surface area. The sensor module is configured to drive a sensing signal on a first subset of sensor electrodes of the plurality of sensor electrodes and receive a resulting signal on a second subset of sensor electrodes of the plurality of sensor electrodes. Each of the sensor electrodes from the first subset of sensor electrodes shares a boundary with a sensor electrode of the second subset of sensor electrodes.

Drawings

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments and are therefore not to be considered limiting of its scope, for other effective embodiments may be admit to other effective embodiments.

Fig. 1 is a block diagram of a system including an input device according to an example.

Fig. 2 is a block diagram depicting a capacitive sensor device, in accordance with an embodiment of the present disclosure.

Fig. 3 schematically illustrates a sensor electrode pattern that may be used to sense an input object in a sensing area of a capacitive sensor according to one embodiment of the present disclosure.

FIG. 4 schematically illustrates another embodiment of the sensor electrode pattern of FIG. 3.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements of one embodiment may be beneficially incorporated in other embodiments.

Detailed Description

The following detailed description is merely exemplary in nature and is not intended to limit the embodiments or the application and uses of such embodiments. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

Various embodiments provide circular, single layer sensor electrode patterns for input devices such as wearable devices. The sensor electrode pattern features transmitter electrodes and receiver electrodes laid out in an alternating manner such that each "receiver" electrode is surrounded by a "transmitter" electrode. The individual sensor electrodes of the described pattern are designed to provide substantially the same electrode area size across the sensor. In addition, the sensor electrode pattern is arranged to be symmetrical across both the horizontal axis and the vertical axis. The provided characteristics of the sensor electrode pattern result in the sensor structure having the same absolute capacitive sensing measurement for all sensor electrodes and the same transcapacitive sensing measurement for all "pixels".

The described embodiments provide improved performance for capacitive sensing along the rounded edges of the sensor device as compared to conventional single layer sensor patterns. Further, using the described sensor electrode patterns, the number and arrangement of sensor electrodes allows for a narrower border area around the sensor pattern for edge-tracking routing and for a reduced size of the bonding region for coupling the sensor to the processor system, such as an Anisotropic Conductive Film (ACF), for example.

Turning now to the drawings, FIG. 1 is a block diagram of an exemplary input device 100 according to an embodiment of the present invention. The input device 100 may be configured to provide input to an electronic system (not shown). As used in this document, the term "electronic system" (or "electronic device") generally refers to any system capable of electronically processing information. Some non-limiting examples of electronic systems include personal computers of all sizes and shapes, such as desktop computers, laptop computers, netbooks, tablets, web browsers, e-book readers, and Personal Digital Assistants (PDAs). Additional example electronic systems include composite input devices, such as a physical keyboard that includes input device 100 and separate rocker or key switches. Further example electronic systems include peripherals such as data input devices (including remote controls and mice), and data output devices (including display screens and printers). Other examples include remote terminals, kiosks, and video game machines (e.g., video game consoles, portable gaming devices, and the like). Other examples include communication devices (including cellular telephones such as smart phones) and media devices (including recorders, editors, and players such as televisions, set-top boxes, music players, digital photo frames, and digital cameras). In addition, the electronic system may be a master or a slave of the input device.

The input device 100 may be implemented as a physical component of an electronic system or may be physically separate from the electronic system. As appropriate, the input device 100 may communicate with the components of the electronic system using any one or more of the following: buses, networks, and other wired or wireless interconnections. Examples include I²C. SPI, PS/2, Universal Serial Bus (USB), Bluetooth, RF, and IRDA.

In fig. 1, the input device 100 is shown as a proximity sensor device (also often referred to as a "touchpad" or "touch sensor device") configured to sense input provided by one or more input objects 140 in a sensing region 120. As shown in fig. 1, example input objects include fingers and a stylus.

Sensing region 120 encompasses any space above, around, within, and/or near input device 100 in which input device 100 is capable of detecting user input (e.g., user input provided by one or more input objects 140). The size, shape, and location of the particular sensing region may vary widely from embodiment to embodiment. In some embodiments, sensing region 120 extends in one or more directions into space from the surface of input device 100 until the signal-to-noise ratio prevents sufficiently accurate object detection. In different embodiments, the distance that the sensing region 120 extends in a particular direction may be on the order of less than a millimeter, centimeter, or more, and may vary significantly with the type of sensing technology used and the degree of accuracy required. Thus, some embodiments sense input that includes no contact with any surface of input device 100, contact with an input surface (e.g., a touch surface) of input device 100, contact with an input surface of input device 100 coupled with an amount of applied force or pressure, and/or combinations thereof. In different embodiments, the input surface may be provided by a surface of a housing in which the sensor electrodes reside, by a panel applied over the sensor electrodes, or any housing, etc. In some embodiments, sensing region 120 has a rectangular shape when projected onto an input surface of input device 100. In some embodiments, sensing region 120 has a circular shape when projected onto an input surface of input device 100.

Input device 100 may use any combination of sensor components and sensing technologies to detect user input in sensing region 120. Input device 100 includes one or more sensing elements for detecting user input. As a few non-limiting examples, input device 100 may use capacitive, inverse capacitive (capacitive), resistive, inductive, magnetic, acoustic, ultrasonic, and/or optical technologies. Some implementations are configured to provide images across a space in one, two, three, or higher dimensions. Some implementations are configured to provide a projection of an input along a particular axis or plane. In some resistive implementations of input device 100, a flexible and conductive first layer is separated from a conductive second layer by one or more spacer elements. During operation, one or more voltage gradients are created across the multiple layers. Pressing the flexible first layer may deflect it sufficiently to create an electrical contact between the layers, producing a voltage output reflecting the contact point(s) between the layers. These voltage outputs may be used to determine positional information.

In some inductive implementations of the input device 100, one or more sensing elements pick up a loop current induced by a resonant coil or coil pair. Some combination of amplitude, phase and frequency of the current may in turn be used to determine locational information.

In some capacitive implementations of the input device 100, a voltage or current is applied to create an electric field. A nearby input object causes a change in the electric field and produces a detectable change in the capacitive coupling, which can be detected as a voltage change, a current change, or the like.

Some capacitive implementations use a pattern of arrays or other conventional or unconventional capacitive sensing elements to create an electric field. In some capacitive implementations, separate sensing elements may be resistively shorted together to form larger sensor electrodes. Some capacitive implementations use resistive foils, which may be resistive uniform.

Some capacitive implementations use "self-capacitance" (or "absolute capacitance") sensing methods based on changes in the capacitive coupling between the sensor electrodes and the input object. In various embodiments, an input object near the sensor electrode changes the electric field near the sensor electrode, thereby changing the measured capacitive coupling. In one implementation, the absolute capacitive sensing method operates by modulating the sensor electrode relative to a reference voltage (e.g., system ground) and by detecting capacitive coupling between the sensor electrode and an input object.

Some capacitive implementations use a "mutual capacitance" (or "transcapacitive") sensing method based on changes in the capacitive coupling between the sensor electrodes. In various embodiments, an input object near the sensor electrodes alters the electric field between the sensor electrodes, thereby altering the measured capacitive coupling. In one implementation, a transcapacitive sensing method operates by detecting a capacitive coupling between one or more transmitter sensor electrodes (also called "transmitter electrodes" or "transmitters") and one or more receiver sensor electrodes (also called "receiver electrodes" or "receivers"). The transmitter sensor electrode may be modulated relative to a reference voltage (e.g., system ground) to transmit a transmitter signal. The receiver sensor electrodes may be held substantially constant relative to a reference voltage to facilitate reception of the resultant signal. The composite signal may include the effect(s) corresponding to one or more transmitter signals and/or to one or more sources of environmental interference (e.g., other electromagnetic signals). The sensor electrodes may be dedicated transmitters or receivers, or the sensor electrodes may be configured to both transmit and receive. Alternatively, the sensor electrodes may be modulated with respect to ground.

In fig. 1, processing system 110 is shown as part of input device 100. The processing system 110 is configured to operate the hardware of the input device 100 to detect input in the sensing region 120. The processing system 110 includes some or all of one or more Integrated Circuits (ICs) and/or other circuit components. For example, a processing system for a mutual capacitance sensor device may include transmitter circuitry configured to transmit signals with transmitter sensor electrodes and/or receiver circuitry configured to receive signals with receiver sensor electrodes. In some embodiments, the processing system 110 also includes electronically readable instructions, such as firmware code, software code, and/or the like. In some embodiments, the components making up processing system 110 are placed together, such as near the sensing element(s) of input device 100. In other embodiments, the components of processing system 110 are physically separate from one or more components proximate to the sensing element(s) of input device 100 and one or more components elsewhere. For example, input device 100 may be a peripheral coupled to a desktop computer, and processing system 110 may include software configured to run on the central processing unit of the desktop computer and one or more ICs (possibly with associated firmware) separate from the central processing unit. As another example, the input device 100 may be physically integrated in a phone, and the processing system 110 may include circuitry and firmware that are part of the main processor of the phone. In some embodiments, the processing system 110 is dedicated to implementing the input device 100. In other embodiments, processing system 110 also performs other functions, such as operating a display screen, driving haptic actuators, and the like.

The processing system 110 may be implemented as a set of modules that handle different functions of the processing system 110. Each module may include circuitry that is part of the processing system 110, firmware, software, or a combination thereof. In different embodiments, different combinations of modules may be used. Example modules include a hardware operation module for operating hardware such as sensor electrodes and a display screen, a data processing module for processing data such as sensor signals and positional information, and a reporting module for reporting information. Further example modules include a sensor operation module configured to operate the sensing element(s) to detect an input, a recognition module configured to recognize a gesture, such as a mode change gesture, and a mode change module to change the mode of operation.

In some embodiments, the processing system 110 responds to user input (or lack of user input) in the sensing region 120 directly by causing one or more actions. Example actions include changing operating modes, and GUI actions such as pointer movement, selection, menu navigation, and other functions. In some embodiments, the processing system 110 provides information about the input (or lack of input) to certain portions of the electronic system (e.g., to a central processing system of the electronic system that is separate from the processing system 110, if such a separate central processing system exists). In some embodiments, certain portions of the electronic system process information received from the processing system 110 to act on user input, such as to facilitate a full range of actions including mode change actions and GUI actions.

For example, in some embodiments, processing system 110 operates the sensing element(s) of input device 100 to generate electrical signals indicative of an input (or lack of input) in sensing region 120. The processing system 110 may perform any suitable number of processes on the electrical signals in generating the information provided to the electronic system. For example, the processing system 110 may digitize analog electrical signals obtained from the sensor electrodes. As another example, the processing system 110 may perform filtering or other signal conditioning. As yet another example, the processing system 110 may subtract or otherwise account for the baseline so that the information reflects the difference between the electrical signal and the baseline. As yet further examples, the processing system 110 may determine positional information, recognize an input as a command, recognize handwriting, and the like.

As used herein, "positional information" broadly includes absolute position, relative position, velocity, acceleration, and other types of spatial information. Exemplary "zero-dimensional" positional information includes near/far or contact/no-contact information. Exemplary "one-dimensional" positional information includes position along an axis. Exemplary "two-dimensional" positional information includes in-plane motion. Exemplary "three-dimensional" positional information includes instantaneous or average velocity in space. Further examples include other representations of spatial information. Historical data regarding one or more types of locality information may also be determined and/or stored, including, for example, historical data tracking location, motion, or instantaneous speed over time.

In some embodiments, input device 100 is implemented with additional input components that are operated on by processing system 110 or by some other processing system. These additional input components may provide redundant functionality, or some other functionality, for inputs in the sensing region 120. FIG. 1 shows buttons 130 near sensing region 120, which buttons 130 can be used to assist in selecting items using input device 100. Other types of additional input components include sliders, balls, rollers, switches, and the like. Conversely, in some embodiments, input device 100 may be implemented without other input components.

In some embodiments, input device 100 includes a touch screen interface and sensing area 120 overlaps at least a portion of an activation area of a display screen. For example, input device 100 may include substantially transparent sensor electrodes that overlap a display screen and provide a touch screen interface for an associated electronic system. The display screen may be any type of dynamic display capable of displaying a visual interface to a user, and may include any type of Light Emitting Diode (LED), organic LED (oled), Cathode Ray Tube (CRT), Liquid Crystal Display (LCD), plasma, electro-luminescence (EL), or other display technology. Input device 100 and the display screen may share physical elements. For example, some embodiments may use some of the same electronic components for display and sensing. As another example, the display screen may be operated in part or in whole by the processing system 110.

It should be understood that while many embodiments of the invention are described in the context of a fully functional apparatus, aspects of the invention are capable of being distributed as a program product (e.g., software) in a variety of forms. For example, aspects of the invention can be implemented and distributed as a software program on an information bearing medium readable by an electronic processor (e.g., a non-transitory computer-readable and/or recordable/writable information bearing medium readable by the processing system 110). In addition, embodiments of the invention apply equally regardless of the particular type of medium used to carry out the distribution. Examples of non-transitory electronically readable media include various disks, memory sticks, memory cards, memory modules, and the like. The electronically readable storage medium may be flash memory based, optical, magnetic, holographic, or any other storage technology.

Fig. 2 is a block diagram depicting a capacitive sensor device 200, in accordance with an embodiment of the present disclosure. The capacitive sensor device 200 includes an example implementation of the input device 100 shown in fig. 1. The capacitive sensor device 200 includes a sensor electrode pattern 202 coupled to an example implementation of the processing system 110. The sensor electrode pattern 202 is arranged on a substrate 204 to provide the sensing region 120. Sensor electrode pattern 202 includes a plurality of sensor electrodes 210 disposed on substrate 204_J,K(collectively referred to as sensor electrodes 210). In the present example, the sensor electrode pattern 202 includes a plurality of sensor electrodes 210 arranged in a rectangular matrix, specifically, arranged in J rows and K columns, where J and K are positive integers, although one of J and K may be zero. For clarity of illustration and description, FIG. 2 presents the sensing elements in a rectangular matrix, and does not show the different components in detail, such as the processing system 110 and the different interconnections between the sensing elements. The detailed sensor electrode pattern is described later in connection with fig. 3 and 4.

The sensor electrodes 210 are generally electrically insulated from each other. In addition, in the case where the sensor electrode 210 includes a plurality of sub-electrodes, the sub-electrodes may be insulated from each other in resistance. In one embodiment, all of the sensor electrodes 210 may be disposed on a single layer of the substrate 204. In some embodiments, although the sensor electrodes are shown disposed on a single substrate 204, the sensor electrodes may be disposed on more than one substrate. For example, some sensor electrodes may be disposed on a first substrate, while other sensor electrodes may be disposed on a second substrate adhered to the first substrate.

Processing system 110 is coupled to sensor electrodes 210 by conductive path traces 206 to implement sensing region 120 for sensing inputs. Each sensor electrode 210 may be coupled to at least one of the routing traces 206. The processing system 110 may also be coupled to the grid electrode by one or more routing traces (not shown for clarity). Processing system 110 is coupled to sensor electrodes 210 by conductive path traces 206 to implement sensing region 120 for sensing inputs.

Capacitive sensor device 200 may be used to communicate user input (e.g., a user's finger, a probe such as a stylus, and/or some other external input object) to an electronic system (e.g., a computing device or other electronic device). For example, capacitive sensor device 200 may be implemented as a capacitive touch screen device that may be placed over an underlying image or information display device (not shown). In this manner, a user will view the underlying image or information display by looking through the substantially transparent elements in sensor electrode pattern 202. When implemented in a touch screen, the substrate 204 may include at least one substantially transparent layer (not shown). The sensor electrodes and conductive path traces may be formed from a substantially transparent conductive material. Indium Tin Oxide (ITO) and/or thin, barely visible wires are but two of many possible examples of substantially transparent materials that may be used to form sensor electrodes and/or conductive path traces. In other examples, the conductive path traces may be formed from an opaque material and, in turn, hidden in a border area (not shown) of the sensor electrode pattern 202.

In another example, the capacitive sensor device 200 can be implemented as a capacitive touchpad, slider, button, or other capacitive sensor. For example, substrate 204 can be implemented with, but is not limited to, one or more clear or opaque materials. Likewise, clear or opaque conductive materials may be used to form sensor electrodes and/or conductive path traces for sensor electrode pattern 202.

In general, the processing system 110 excites or drives the sensing elements of the sensor electrode pattern 202 with the sensing signals, and the processing system 110 measures induced or generated signals that include the sensing signals and input contributions in the sensing region 120. The terms "actuating" and "driving" as used herein include controlling some electrical aspect of the driven element. For example, it is possible to drive a current through a wire, drive a charge into a conductor, drive a substantially constant or varying voltage waveform onto an electrode, and the like. The sensing signal may be constant, substantially constant, or time varying, and typically includes shape, frequency, amplitude, and phase. The sense signal may be referred to as an "active signal" as opposed to a "passive signal" such as a ground signal or other reference signal. The sense signal may also be referred to as a "transmitter signal" when used in transcapacitive sensing, and may also be referred to as an "absolute sense signal" or a "modulated signal" when used in absolute sensing.

In an example, the processing system 110 drives the sensing element(s) of the sensor electrode pattern 202 with a voltage and senses a resulting corresponding charge on the sensing element(s). That is, the signal generated when the sense signal is a voltage signal is a charge signal (e.g., a signal indicative of accumulated charge, such as an integrated current signal). Capacitance is proportional to the applied voltage and inversely proportional to the accumulated charge. The processing system 110 may determine the measurement(s) of capacitance from the sensed charge. In another example, the processing system 110 drives the sensing element(s) of the sensor electrode pattern 202 with an electrical charge and senses a corresponding voltage generated across the sensing element(s). That is, the sensing signal is a signal (e.g., a current signal) that causes charge accumulation and the resulting signal is a voltage signal. The processing system 110 may determine the measurement(s) of capacitance from the sensed voltage. In general, the term "sense signal" is meant to include both drive voltages to sense charge and drive charges to sense voltage, and any other type of signal that may be used to obtain a capacitive signature. "capacitance signature" includes measurements of charge, current, voltage, etc., from which capacitance can be derived.

The processing system 110 may include a sensor module 212 and a determination module 214. The sensor module 212 and the determination module 214 include modules that perform different functions of the processing system 110. In other examples, different configurations of one or more other modules 216 may perform the functions described herein. The sensor module 212 and the determination module 214 may include circuitry, and may further include firmware, software, or a combination thereof that operates in cooperation with the circuitry.

According to one or more schemes ("excitation schemes"), the sensor module 212 selectively drives the sensing signal(s) on one or more sensing elements of the sensor electrode pattern 202 over one or more cycles ("excitation cycles"). During each excitation period, the sensor module 212 may selectively sense the resulting signal(s) from one or more sensing elements of the sensor electrode pattern 202. Each excitation period has an associated time period during which the sensing signal is driven and the resulting signal is measured.

In one type of excitation scheme, the sensor module 212 may selectively drive the sensing elements of the sensor electrode pattern 202 for absolute capacitive sensing. In absolute capacitive sensing, the sensor module 212 may measure a voltage, charge, or current on the sensor electrode(s) 210 to obtain a resulting signal indicative of a capacitance between the sensor electrode(s) 210 and an input object. In such an excitation scheme, a measure of the absolute capacitance between the selected sensing element(s) and the input object(s) is determined from the generated signal(s).

In another type of excitation scheme, the sensor module 212 can selectively drive the sensing elements of the sensor electrode pattern 202 for transcapacitive sensing. In transcapacitive sensing, sensor module 212 drives selected transmitter sensor electrodes with transmitter signal(s) and senses resulting signals from selected receiver sensor electrodes. In such an excitation scheme, a measure of the cross-over capacitance between the transmitter and receiver electrodes is determined from the resulting signal. In an example, the sensor module 212 may drive selected sensor electrodes 210 with the transmitter signal(s) and receive resulting signals from other ones of the sensor electrodes 210.

During any actuation period, the sensor module 212 may drive the sensing elements of the sensor electrode pattern 202 with other signals, including the reference signal and the guard signal. That is, those sensing elements of sensor electrode pattern 202 that are not driven with a sensing signal, or that are not sensed to receive a resulting signal, may be driven with a reference signal, a guard signal, or left floating (i.e., not driven with any signal). The reference signal may be a ground signal (e.g., system ground) or any other constant or substantially constant voltage signal. The guard signal may be a signal that is similar or identical to the transmitter signal in at least one of shape, amplitude, frequency, or phase of the transmitter signal.

"system ground" may indicate a common voltage shared by system components. For example, a capacitive sensing system of a mobile phone may sometimes refer to a system ground provided by a power source (e.g., a charger or power source) of the phone. The system ground may not be fixed relative to the earth or other reference. For example, mobile phones on a desk typically have a floating system ground. A mobile phone held by a person who is strongly coupled to earth ground through free space may be grounded with respect to the person, but the person ground may vary with respect to the earth ground. In many systems, the system ground is connected to or provided by the largest area electrode in the system. The capacitive sensor device 200 may be disposed proximate to such a system ground electrode (e.g., disposed above a ground plane or backplane).

The determination module 214 performs capacitance measurements based on the generated signals obtained by the sensor module 212. The capacitance measurement may include a change in capacitive coupling between elements (also referred to as a "change in capacitance"). For example, the determination module 214 may determine a baseline measurement of capacitive coupling between elements without the presence of the input object(s). The determination module 214 may then combine the baseline measurement of the capacitive coupling with the measurement of the capacitive coupling in the presence of the input object(s) to determine a change in the capacitive coupling.

In an example, the determination module 214 may perform a plurality of capacitance measurements associated with a particular portion of the sensing region 120 as "capacitive pixels" to create a "capacitive image" or "capacitive frame. The capacitive pixels of the capacitive image represent locations within the sensing region 120 where capacitive coupling can be measured using the sensing elements of the sensor electrode pattern 202. For example, a capacitive pixel may correspond to sensor electrode 210_1,1With another sensor electrode 210 affected by the input object(s)_1,2Across the capacitance coupling between them. In another example, the capacitive pixels may correspond to the absolute capacitance of the sensor electrodes 210. The determination module 214 may determine an array of capacitive coupling variations using the generated signals obtained by the sensor module 212 to generate capacitive pixels that form an x by y array of capacitive images. The capacitive image may be obtained using transcapacitive sensing (e.g., transcapacitive images), or may be obtained using absolute capacitive sensing (e.g., absolute capacitive images). In this manner, the processing system 110 may capture a capacitive image that is a snapshot of the measured response related to the input object(s) in the sensing region 120. A given capacitive image may include all of the capacitive pixels in the sensing area, or only a subset of the capacitive pixels.

In another example, the determination module 214 may perform a plurality of capacitance measurements associated with a particular axis of the sensing region 120 to create a "capacitive distribution" along that axis. For example, the determination module 214 may determine the edge passing by the sensor electrode 210_X,YAnd/or sensor electrode 210_X+1,YAn array of absolute capacitive coupling variations of the defined axes to produce the capacitive profile(s). The array of capacitive coupling variations may comprise less than or equal to along a given axisA large number of points of the number of sensor electrodes.

The capacitance measurement(s) by the processing system 110, such as the capacitive image(s) or capacitive profile(s), enable sensing of contact, hover, or other user input with respect to the sensing region formed by the sensor electrode pattern 202. The determination module 214 may use the measurements of capacitance to determine positional information about user input related to the sensing region formed by the sensor electrode pattern 202. The determination module 214 may additionally or alternatively use such measurement(s) to determine an input object size and/or an input object type.

Conventional grid sensor patterns are typically composed of sensor electrodes arranged in rows and columns for capacitive sensing using a cartesian grid configuration. However, such sensors may not perform as well when used on circular shapes such as wearable devices (e.g., smartwatches) and other electronic devices that are becoming popular in the marketplace. Therefore, there is a need for a sensor electrode pattern for a circular sensor profile that better utilizes circular geometry.

Fig. 3 schematically illustrates a sensor electrode pattern 300 that may be used to sense an input object in the sensing region 120 of a capacitive sensor according to one embodiment of the present disclosure. Sensor electrode pattern 300 includes a plurality of sensor electrodes that may be divided into a first plurality of sensor electrodes 302 and a second plurality of sensor electrodes 304. Different fill patterns are used in fig. 3 to distinguish different subsets of sensor electrodes. Each of the

sensor electrodes

302, 304 can be coupled to one or more components of the processing system 110 (such as the sensor module 212 of fig. 1) by dedicated traces or other paths disposed between the

multiple sensor electrodes

302, 304. For purposes of discussion, the sensor electrodes 302 are labeled as transmitter electrodes Tx 1 through Tx 16, while the sensor electrodes 304 are labeled as receiver electrodes Rx1 through Rx 16, although other numbers of sensor electrodes may be used.

In one embodiment, the plurality of

sensor electrodes

302, 304 are both disposed on a single layer of the substrate 350. For example, the plurality of

sensor electrodes

302, 304 and associated conductive path traces may form a substantially transparent layer made of a material such as Indium Tin Oxide (ITO) and/or thin, barely visible wires. In one embodiment, the plurality of

sensor electrodes

302, 304 are disposed as a substantially transparent layer on an upper surface of a color filter glass of a display device.

In one or more embodiments, the

sensor electrodes

302, 304 are arranged in a symmetrical circular pattern. The

sensor electrodes

302, 304 are arranged in a circular pattern such that the

sensor electrodes

302, 304 are symmetrical along a first (vertical) axis 310. Such symmetry divides the sensor electrode pattern 300 into two halves. In some embodiments, the

sensor electrodes

302, 304 may be further arranged in a symmetrical circular pattern that is also symmetrical along a second (horizontal) axis 312 that is orthogonal to the vertical axis 310. This additional symmetry effectively divides the sensor electrode pattern 300 into quarters. The symmetrical nature of the sensor electrode pattern 300 enables a connected processing system, such as processing system 110, to use simplified logic for determining positional information based on the resulting signals obtained from the sensor electrodes. That is, the processing system 110 may use the same logic for determining a single quarter or half of the positional information, but apply to the other quarters or halves in a round-robin fashion.

In one embodiment, the

sensor electrodes

302, 304 of the sensor electrode pattern 300 may be arranged in an inner circle 308 of sensor electrodes and an outer circle 306 of sensor electrodes radially arranged outward from the inner circle 308 of sensor electrodes. In the depicted embodiment, the inner circle 308 is comprised of eight sensor electrodes (i.e., Tx 3, Rx3, Tx 6, Rx 6, Tx 11, Rx 11, Tx 14, and Rx 14), while the outer ring 306 is comprised of twenty-four sensor electrodes (i.e., Tx 1, Rx1, Tx 2, Rx 2, Tx4, Rx 4, Tx 5, etc.).

In one or more embodiments, each sensor electrode in pattern 300 has a surface area substantially equal to the other sensor electrodes in the pattern. The relatively same area of the sensor electrodes provides more consistent performance during absolute capacitive sensing. The sensor electrodes in pattern 300 may be arranged in a tiling configuration (tiling) with alternating sensor electrodes 302 ("transmitter electrodes") and sensor electrodes 304 ("receiver electrodes") such that each sensor electrode is surrounded by and shares a boundary with other types of sensor electrodes. For example, sensor electrode Rx1 is adjacently placed next to sensor electrodes Tx 1 and Tx 2 (of inner circle 308) and sensor electrode Tx 3 (of outer circle 306). In another example, the sensor electrode Tx 3 is placed adjacently next to the sensor electrodes Rx1, Rx3, and Rx 14.

The geometric design of the sensor electrode pattern 300 is selected and arranged to obtain substantially equal surface areas between the sensor electrodes. In some embodiments, each

sensor electrode

302, 304 may have a wedge shape consisting of two macroscopically straight edges and a macroscopically curved edge. In the illustrated embodiment, each

sensor electrode

302, 304 in the outer ring 306 has two macroscopically straight edges 320 and either macroscopically convex edges 322 or macroscopically concave edges 324. All concave edges 324 of the

sensor electrodes

302, 304 form the inner circumference of the outer ring 306, while convex edges 326 of the

sensor electrodes

302, 304 arranged in the outer ring 306 form the outer circumference of the outer ring 306. Each

sensor electrode

302, 304 in the inner circle 308 has two macroscopically straight edges 320 and a macroscopically raised edge 326, which raised edges 326 together form the outer circumference of the inner circle 308. The convex edge 326 of the sensor electrode in the inner circle 308 abuts the concave edge 324 of the sensor electrode in the outer ring 306.

The term "macroscopically" as used herein means that the sensor electrode pattern 300 is depicted as a generalized geometric pattern. Those skilled in the art will recognize that each sensor electrode may be configured to interleave or cross each other to maximize the length of the adjoining edges of the sensor electrodes to improve capacitive coupling between the electrodes. As depicted in the inset of fig. 3, the sensor electrode 302 may have an electrode shape comprising a plurality of recessed regions 332, wherein the respective protruding regions 330 of the second type of sensor electrode (e.g. sensor electrode 304) are arranged in the recessed regions 332. The sensor electrodes 302 may likewise have protruding regions disposed within recessed regions of other sensor electrodes. The increased length of the abutting edges may optimize the ratio of (e.g., interfering) direct coupling of the user input signal with respect to the input within either electrode. Other different shapes and geometric configurations may be used to interleave or interdigitate adjacent sensor electrodes. A "macroscopically" straight edge of a sensor electrode refers to a substantially straight edge that the sensor electrode should have, if not for reasons of interdigitation and other features made along that edge of the sensor electrode. Similarly, a "macroscopically" curved edge of a sensor electrode refers to a substantially curved edge that the sensor electrode should have, if not for interleaving and other features made along that edge of the sensor electrode.

As discussed above, the processing system 110 may operate the

sensor electrodes

302, 304 according to a plurality of excitation schemes, including the excitation scheme(s) for mutual capacitance sensing ("transcapacitive sensing") and/or self capacitance sensing ("absolute capacitive sensing"). In a transcapacitive excitation scheme, processing system 110 (of fig. 1) may use multiple sets of sensor electrodes in sensor electrode pattern 300 to detect the presence of an input object by transcapacitive sensing. The sensor module 212 may drive at least one of the sensor electrodes 302 by a transmitter signal (the sensor electrode 302 is a "transmitter electrode") and may receive a resulting signal from a sensor electrode 304 that shares a boundary with the driven sensor electrode 302 (the sensor electrode 304 is a "receiver electrode"). In other embodiments, sensor electrodes 304 may be transmitter electrodes and sensor electrodes 302 may be receiver electrodes. The determination module 214 uses the generated signals to determine a transcapacitive measurement and form a capacitive image.

In an absolute capacitive sensing scheme, the processing system 110 may use at least one

sensor electrode

302, 304 to detect the presence of an input object by absolute capacitive sensing. The sensor module 212 may measure a voltage, charge, or current on the sensor electrode(s) 302, 304 to obtain a resulting signal indicative of a capacitance between the sensor electrode(s) and an input object. The determination module 214 uses the generated signal to determine an absolute capacitance measurement. The input device 100 may be configured to operate with any of the schemes described above. The input device 100 may also be configured to switch between any two or more of the schemes described above.

Fig. 4 schematically illustrates another embodiment of a sensor electrode pattern 400 that may be used to sense an input object in a sensing region 120 of a capacitive sensor according to another embodiment of the present disclosure. Sensor electrode pattern 400 is configured similarly to sensor electrode pattern 300 except for having a simplified, reduced sensor electrode configuration. The sensor electrode pattern 400 includes a plurality of sensor electrodes that may be divided into first and

second subsets

402, 404 of sensor electrodes. Different fill patterns are used in fig. 4 to distinguish different subsets of sensor electrodes. Each of the

sensor electrodes

402, 404 may be coupled to one or more components of the processing system 110 (such as the sensor module 212 of fig. 1) by dedicated traces or other paths disposed between the plurality of

sensor electrodes

402, 404.

As shown in fig. 4, the sensor electrodes 402 have been labeled as transmitter electrodes Tx 1 through Tx 8, while the sensor electrodes 404 are labeled as receiver electrodes Rx1 through Rx 8, although other numbers of sensor electrodes may be used. In one embodiment, the

sensor electrodes

402, 404 of the sensor electrode pattern 400 may be arranged in an inner circle 408 of sensor electrodes and an outer circle 406 arranged radially outward from the inner circle 408. In the example shown, the inner circle 408 is comprised of four sensor electrodes (i.e., Tx 2, Rx 2, Tx 6, Rx 6), while the outer circle 406 is comprised of twelve sensor electrodes (i.e., Tx 1, Rx1, Tx 3, Rx3, Tx4, Rx 4, Tx 5, Rx 5, Tx 7, Rx 7, Tx 8, Rx 8, etc.).

In one or more embodiments, the sensor electrodes of sensor electrode pattern 400 are arranged in a symmetrical circular pattern. The

sensor electrodes

402, 404 are arranged in a circular pattern such that the

sensor electrodes

402, 404 are symmetrical along a first (vertical) axis 410 and also symmetrical along a second (horizontal) axis 412. Each sensor electrode in pattern 400 has a surface area substantially equal to the other sensor electrodes in the pattern. The sensor electrodes in pattern 400 may be arranged in a tiled configuration with sensor electrodes 402 ("transmitter electrodes") and sensor electrodes 404 ("receiver electrodes") alternating such that each sensor electrode is surrounded by other types of sensor electrodes.

Thus, the embodiments and examples set forth herein are presented to best explain the present invention and its particular application and to thereby enable those skilled in the art to make and utilize the invention. Those skilled in the art, however, will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed.

Claims

1. A capacitive sensor, comprising:

a sensor substrate; and

a plurality of sensor electrodes disposed on a first face of the sensor substrate, wherein the plurality of sensor electrodes includes a plurality of first sensor electrodes defining an inner circle within a symmetrical circular pattern and further includes a plurality of second sensor electrodes defining an outer circle within a symmetrical circular pattern and disposed radially outward from the inner circle;

wherein the plurality of sensor electrodes are configured to sense an input object in a sensing area of the capacitive sensor;

wherein the plurality of sensor electrodes are arranged in a tiled configuration, wherein the first plurality of sensor electrodes and the second plurality of sensor electrodes each have an alternating pattern of sensor electrodes of a first type and sensor electrodes of a second type; and

wherein each of the plurality of first sensor electrodes and the plurality of second sensor electrodes have an equal surface area.

2. A capacitive sensor according to claim 1 in which the symmetrical circular pattern is symmetrical along a first axis and along a second axis, the second axis being orthogonal to the first axis.

3. A capacitive sensor according to claim 1 in which each of the first and second sensor electrodes defines two macroscopically rectilinear edges and one macroscopically curved edge.

4. A capacitive sensor according to claim 1, wherein each of the first sensor electrodes defines a macroscopically convex edge and each of the second sensor electrodes defines at least one of a macroscopically convex edge and a macroscopically concave edge.

5. A capacitive sensor according to claim 1 in which the capacitive sensor comprises a touch screen and the plurality of sensor electrodes are arranged on a display device.

6. A capacitive sensor according to claim 1 in which the first face of the sensor substrate comprises an upper surface of a colour filter of a display device.

7. A capacitive sensor according to claim 1 in which in the laid configuration at least one electrode of a first type borders at least two other sensor electrodes of a second type comprising at least one of the plurality of first sensor electrodes within the inner circle and at least one of the plurality of second sensor electrodes within the outer circle.

8. A capacitive sensor according to claim 7 in which at least one electrode of the first type defines a boundary, wherein at least two other sensor electrodes of the second type substantially surround the boundary.

9. The capacitive sensor of claim 7, wherein each of the plurality of first sensor electrodes borders at least two other sensor electrodes of the second type.

10. A capacitive sensor device, comprising:

a sensor substrate;

a plurality of sensor electrodes arranged on a first face of the sensor substrate and arranged in a symmetrical circular pattern, wherein the plurality of sensor electrodes are configured to sense an input object in a sensing area of the capacitive sensor device;

wherein each of the plurality of sensor electrodes has an equal surface area; and

a processing system communicatively coupled to the plurality of sensor electrodes and configured to:

performing mutual capacitive sensing by driving sensing signals on a first subset of the plurality of sensor electrodes and receiving resulting signals on a second subset of the plurality of sensor electrodes, wherein each sensor electrode of the first subset shares a boundary with one or more sensor electrodes of the second subset; and

absolute capacitive sensing is performed with the plurality of sensor electrodes.

11. A capacitive sensor device according to claim 10, wherein the symmetrical circular pattern is symmetrical along a first axis and along a second axis, the second axis being orthogonal to the first axis.

12. The capacitive sensor device of claim 10, wherein each of said plurality of sensor electrodes defines two macroscopically straight edges and one macroscopically curved edge.

13. The capacitive sensor device of claim 10, wherein the plurality of sensor electrodes comprises:

a plurality of first sensor electrodes defining an inner circle within a symmetrical circular pattern; and

a plurality of second sensor electrodes defining an outer ring within a symmetrical circular pattern and arranged radially outward from the inner ring.

14. The capacitive sensor device of claim 13, wherein each of the first sensor electrodes defines a macroscopically convex edge and each of the second sensor electrodes defines at least one of a macroscopically convex edge and a macroscopically concave edge.

15. The capacitive sensor device of claim 13, wherein the plurality of first sensor electrodes and the plurality of second sensor electrodes are each arranged in a laid-up configuration with the first subset of sensor electrodes alternating with the second subset of sensor electrodes.

16. A capacitive sensor device according to claim 10, wherein the first face of the sensor substrate comprises an upper surface of a colour filter of a display device.

17. A processing system for a touch screen device, the processing system comprising:

a sensor module communicatively coupled to a plurality of sensor electrodes, wherein the plurality of sensor electrodes are arranged on a first face of a sensor substrate and are arranged in a symmetrical circular pattern, wherein the plurality of sensor electrodes are configured to sense input objects in a sensing area of the touch screen device, wherein each of the plurality of sensor electrodes has an equal surface area, wherein the sensor module is configured to:

driving sensing signals on a first subset of the plurality of sensor electrodes;

receiving the resulting signals on a second subset of the plurality of sensor electrodes; and

wherein each sensor electrode of the first subset shares a boundary with one or more sensor electrodes of the second subset.

18. The processing system of claim 17, wherein the symmetrical circular pattern is symmetrical along a first axis and along a second axis, the second axis being orthogonal to the first axis.

19. The processing system of claim 17, wherein each of the plurality of sensor electrodes defines two macroscopically straight edges and one macroscopically curved edge.

20. The processing system of claim 17, wherein the plurality of sensor electrodes comprises:

21. The processing system of claim 20, wherein each of the first sensor electrodes defines a macroscopically convex edge and each of the second sensor electrodes defines at least one of a macroscopically convex edge and a macroscopically concave edge.

22. The processing system of claim 20, wherein the plurality of first sensor electrodes and the plurality of second sensor electrodes are each arranged in a tiled configuration alternating the first subset of sensor electrodes and the second subset of sensor electrodes.